You can check for yourselves the possibilities of weather in Puerto Plata and the Caribbean in general. If there is not a tropical wave in the area, chances are that the normal weather for the Caribbean -- partly cloudy with scattered showers (mostly in the afternoon or evening) will come true.
Weather forecasts that are posted online are very inaccurate. We tested several of them and they were wrong 8 out of 10 times.
Chances are you will have good weather when you come. Let us know when you get back.